Fig 5.

Mg²⁺ and Sr²⁺ can partially rescue the secretion defect of the ΔrfaL mutant. Wild-type, ΔrfaL, and ΔyscU strains were grown at 37°C in buffered DMEM with or without EGTA, CaCl₂, SrCl₂, or MgSO₄ added to the medium. Following incubation, cultures were centrifuged to separate secreted proteins (S) from cells (P). Proteins in both fractions were trichloroacetic acid precipitated and immunoblotted using antibodies against YscD, YopE, YopD, and RpoA.